>>30869923>>30870032>Though, I don't understand the thing he does with his hand that makes him look like he has Parkinsons.It's a Japanese trope.
Children around that age often try to emulate anime and want to appear cool, so they make up edgy powers and backstories for themselves.
Two of the most common ones, to the point that now they're just comedy tropes, are the "I have an evil power sealed in my eye, and that's why I keep it covered" and, like in this case, "There's a demon/evil spirit/ancient power sealed in my arm".
